Serum markers in breast cancer management

Evaluation of Critical Differences of CEA and CA15.3 Levels in Serial Samples from Patients Operated for Breast Cancer

In the present investigation we evaluated the variability of tumor marker levels in the follow-up of patients without evidence of disease after resection of primary breast cancer. CEA and CA15.3 were measured using commercially available methods in serial blood samples collected from 170 patients. The coefficient of variation among all samples from each patient, which accounts for the total variability (analytical variability + biological variability), was widely scattered (from 4 to 99% for CEA; from 4 to 52% for CA15.3). The critical difference was calculated using the formula designed by Eraser [CD = 2.77. (CVa2 + CVb2)1/2]. It ranged from 11 to 276 for CEA and from 11 to 144 for CA15.3. From the present findings we conclude that:

1) it is possible to identify individually tailored decision criteria to evaluate tumor marker variations in the follow-up of breast cancer patients;

2) in a considerable number of cases the non-tumor-related variability is too high to allow the early identification of minor tumor marker variations that are of clinical relevance.

The Prognostic Significance of Increasing Marker Levels in Metastatic Breast Cancer Patients with Clinically Complete Remission, Partial Remission or Stable Disease

TPS, CA 15-3 and CEA were determined in metastatic breast cancer patients during treatment. After six months of follow-up the patients were divided into four groups according to the UICC criteria for treatment response. Forty-six patients with a more favorable prognosis (complete remission, partial remission or stable disease) were followed for an extended period.

In 30 of the 46 patients at least one marker had increased at the end of the six-month period by at least 25% (TPS in 54%, CA 15-3 in 20%, CEA in 20%). All these 30 patients subsequently developed progression. The prognostic sensitivity was 83%, 30% and 30%, respectively, for TPS, CA 15-3 and CEA. The combination of TPS and CA 15-3 showed a sensitivity of 96%. The median lead time was about 8 months for TPS and CA 15-3, but less than 50% of the patients showed a lead time for CA 15-3 as compared to TPS. We conclude that TPS and CA 15-3 determinations are helpful for the prediction of progression during the follow-up of breast cancer patients.

TPS Monitoring in Metastatic Breast Cancer

The management of metastatic breast cancer patients reflects the heterogeneous nature of the disease. While patients may benefit from hormonal treatment, in most cases more toxic chemotherapy is applied in the advanced stages. The pretreatment levels of TPS in patients with metastatic breast cancer are correlated with prognosis. Decreasing TPS levels (>50%) during treatment are indicative of response. The fastest decrease in TPS levels is obtained in patients with a favorable prognosis. Increasing TPS levels (>25%) predict disease progression with a considerable lead time (median 8 months). The clinical impact of these observations is discussed in this paper.

Tumour marker measurements in the diagnosis and monitoring of breast cancer

Elevation of established blood tumour markers correlates with the stage of breast cancer. The major role of current blood markers is therefore in the diagnosis and monitoring of metastatic disease. A combination of markers is better than a single marker with the most widely adopted combination being CEA and one MUC1 mucin, commonly detected as either CA15.3 or CA27.29. Tumour marker measurement is now used as a complementary test in the diagnosis of symptomatic metastases. In the monitoring of therapeutic response to both endocrine and cytotoxic therapies in advanced disease, biochemical assessment using blood markers not only correlates with conventional UICC criteria but has a lot of advantages which make it a potentially superior way of assessment. In this regard, CA15.3, CEA and ESR are the best validated combination. Studies are ongoing to evaluate the use of sequential blood tumour marker measurements in the follow-up of patients after treatment for their primary breast cancer, in terms of both early detection and early therapeutic intervention. Further randomized studies are also required to ascertain that marker-directed therapy is superior to the current practice for metastatic disease. In line with clinical studies, intensive laboratory work is being carried out to optimize the use of blood markers in advanced disease as well as to exploit their use in screening and diagnosis of early primary breast cancer.

Tissue polypeptide specific antigen (TPS) in breast cancer--an initial evaluation

Tissue Polypeptide Specific-Antigen (TPS), a marker of cell proliferation, was evaluated in 258 patients, 216 with breast carcinoma and 42 with benign breast disease. TPS was measured pre-operatively in 98 patients and correlated with stage of disease showing a progression from Stage I through to Stage IV disease. TPS increased with increasing tumour size, however, TPS levels did not correlate with the number of involved lymph nodes. TPS was measured during follow-up in 118 patients, 64 had no evidence of recurrence, 23 had evidence of loco-regional recurrence and 31 had evidence of metastatic disease. TPS levels were significantly elevated in all categories of recurrence and were highest in patients with disseminated disease. Patients with elevated TPS during follow-up were more likely to experience disease progression on further follow-up. This preliminary study demonstrates that this marker may be useful as an index of tumour burden and deserves further evaluation in a large population to determine whether it can aid in the identification and follow-up of patients with recurrent disease.

CEA, MCA, CA 15.3 and CA 549 and their combinations in expressing and monitoring metastatic breast cancer: a prospective comparative study

Serum levels of carcinoembryonic antigen (CEA), mucin-like carcinoma-associated antigen (MCA), CA 15.3 and CA 549 were concurrently assayed in patients with metastatic breast cancer. Overall sensitivity in detecting metastatic breast cancer (201 pts) was CEA 45%, MCA 59%, CA 15.3 71% and CA 549 72% (P < 0.01). Sensitivity increased by only 6% to 8% when two or more antigens were simultaneously considered. An overall sensitivity of correlation with objective response (n = 71) was observed in the range of 53-67% (P = n.s.) in patients with abnormal baseline marker values, and in the range of 42-87% (P < 0.05) in patients with normal baseline values. The combination of two or more markers did not improve sensitivity, but decreased specificity of correlation with objective response. In conclusion, CA 15.3 and CA 549 have individually higher sensitivity in detecting metastatic breast cancer. No clinical advantage was observed for using two or more markers concurrently over CA 15.3 or CA 549 alone in the monitoring of metastatic breast cancer.

Tumor markers in breast cancer follow-up: a potentially useful parameter still awaiting definitive assessment. Forza Operativa Nazionale sul Carcinoma Mammario (FONCaM)

BACKGROUND

Although tumor markers are frequently used in the follow-up of patients with breast cancer, two points are still being debated: 1) their cost/effectiveness has been neither demonstrated nor disproved; 2) the reliability of the currently used dichotomous division into a positive/negative cut-off should be definitely validated. Dynamic criteria of interpretation based on serial serum samples would probably be more effective for early detection of relapse.

PATIENTS AND METHODS

The aim of the present study was to compare the dichotomous cut-off based decision criteria to a dynamic serial sample based assessment of tumor markers. Since 1989, 794 patients have been followed in 11 institutions. CEA and CA15.3 were measured once a month for three months before every clinical examination. The present paper concerns the evaluation variability in 405 patients without evidence of disease in the first three institutions joining the study.

RESULTS

In patients without evidence of disease, the coefficient of variation of all samples for every patient showed a median value of 19 for CEA and 21 for CA15.3. Variability was negatively associated with the antigen level and was most likely due to the analytical component. This was also confirmed by the significant difference in variability among the three institutions evaluated. The median value of the critical difference was 53% for CEA and 57% for CA15.3.

CONCLUSIONS

1) Individually tailored dynamic decision criteria are applicable in about 50% of the cases. 2) The problem of improving the precision of tumor marker assays in the low dose range must be urgently addressed to the manufacturers of tumor markers by the scientific community in order to apply individually tailored decision criteria for patients in whom the serum level of biological markers is low.

Analytical requirements and standardization of CA 15-3

The CA 15-3 assay could play, probably in combination with cytokeratin markers, a role in the detection of early recurrence and in monitoring therapy in metastatic breast cancer patients. The CA 15-3 assay is, however, not useful for early detection of breast cancer and has no prognostic significance. The analyte is not clearly defined and a primary reference material cannot be synthesized. A reference measurement procedure is not available and many commercial assays use the original Centocor IRMA as such. The comparability of different CA 15-3 assays is not sufficient according to the results of EQAS. The general recommendations of analytical requirements for tumour marker determinations specified by the working group "Quality Control and Standardization" (Hamburger Symposia on Tumour Markers) includes intra-assay and inter-assay precision, drift, carry-over, dilution effect and high-dose hook effect. From a medical point of view reference limits should be established. Specificity/sensitivity profiles should preferentially be represented by ROCcurves. Confounding factors should be analyzed. To improve the clinical value of CA 15-3, the following needs for improvement have been identified: > Standardization of response criteria during treatment; > Definition of significant increase at recurrence; > Investigation of the biological variance during follow-up; > Definition of the analyte; > Preparation of reference material; > Development of an accepted reference method; > Integration of different international activities and > Optimizing decision-making criteria and clinical application.